Laserfiche WebLink
IMPACT AND ABUNDANCE OF AN INTRODUCED CICHLID IN THE LOWER <br />RIO GRANDE (RIO BRAVO DEL NORTE), TEXAS AND MEXICO <br />Robert J. Edwards <br />Pan American University <br />Edinburg, TX 78539 <br />and <br />Michael G. Wood. <br />Del Mar College <br />Corpus Christi, TX 78404 <br />The blue tilapia (Oreochromis aureus) was not recorded from the lower Rio <br />Grande prior to the mid-197U's. The species has since extensively colonized <br />the lower river and has become one of the dominant members of the fish <br />community. Studies conducted since 1980 show extensive ecological overlap <br />between blue tilapia and native fishes. A severe winter cold period in late <br />1983 drastically reduced the blue tilapia population; however, the species <br />rapidly rebounded and reestablished former levels of abundance. In the past <br />3U years, the fish community of the lower Rio Grande has extensively <br />changed. The success of the blue tilapia and the similarity of its ecology <br />to those of the existing fishes, especially the native Rio Grande cichlid <br />(Cichlasoma cyanoguattatum) suggest that such characteristics as generalized <br />food habits, good colonizing ability and adaptability to often stressful <br />environments are important factors in determining the species composition of <br />the fish community. <br />IMPACTU Y ABUNDANCIA DE UNA ESPECIE DE CICLIDAS INTRODUCIDA EN EL BAJO <br />RIO GRANDE (RIO BRAVO DEL NORTE) DE TEXAS Y MEXICO. <br />La tilapia azul (Oreochromis aureus) no ha sido registrada entre las <br />especies del bajo Rio Grande antes de la dd'cada de 1970. Desde entonces, <br />dsta especie ha colonizado extensivamente la parte baja del Rio y se ha <br />convertido en una de las especies dominantes en el area. Los estudios que <br />se han llevado a cabo desde 198U indican una extensa interacidn ecoldgica <br />entre la tilapia azul y ]as especies nativas. El invierno de 1983 fuck <br />severo en ]a regid'n y ]a poblaci6n de tilapia azul fue reducida <br />drdsticamente; sin embargo, la especie ha vuelto a reestablecerse a su nivel <br />anterior de abundancia. En los ultimos 30 affos, la comunidad piscfcola del <br />bajo Rfo Grande ha cambiado extensivamente. E] exito de la tilapia azGl y <br />la similaridad de su ecologfa a las especies locales, especialmente la <br />ciclida nativa del Rfo Grande (Cichlasoma cyanpguttatum) sugieren que <br />algunas caracteristicas como ]os h bitos generales de alimentacion, la <br />habilidad colonizadora y la adaptabilidad a un medio ambiente a menudo <br />dificil, son factores importantes que determinan la composici6n de la <br />comunidad piscfcola. <br />59